The cooling system of modern internal combustion engines plays a crucial role with regard to the pollutant emission and the fuel consumption. The warm-up of an engine can for example be distinctly shortened by switching off the circulation of the coolant flow through the engine block. Thereby, the friction losses are reduced, the fuel consumption reduces, the exhaust gas catalysts reach their operating temperature earlier and therefore start their function earlier. A favorable solution, in order to prevent the flow through the engine in the cold state and to control the coolant temperature actively in an engine at operating state temperature consists in the construction of a thermostatic valve with electric heating and switch-off function. Such thermostatic valves operate today with great reliability. Nevertheless, the requirement arises for a monitoring of the functional capability of the thermostatic valve.
It may be one of many objects of the present invention to configure a thermostatic valve of the type named in the introduction so that its function is monitored in a simple manner, at least with respect to establishing whether the opened or closed valve position of the main valve is present.